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![Page 1: Cerebellum ( 小脑 ) The cerebellum is the second-largest portion of the brain and occupies the inferior and posterior aspects of the cranial cavity. It.](https://reader033.fdocuments.net/reader033/viewer/2022061600/56649e675503460f94b631e7/html5/thumbnails/1.jpg)
Cerebellum
( 小脑 )
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The cerebellum is the second-largest portion of the brain and occupies the inferior and posterior aspects of the cranial cavity. It is posterior to medulla oblongata and pons, and is
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inferior to the occipital
lobes of the cerebrum. It
is separated from the
cerebrum by the
transverse fissure.
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transverse fissure
of cerebrum
midbrain
occipital lobe of cerebrum
The fourth ventricle
Mesencephalic aqueduct
pons
Medulla oblongata
cerebellum
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cerebellum
midbrain
pons
Medulla oblongata
cerebellum
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cerebellu
m
Hypophysis
Dorsal thalamus
The fourth ventricle
Mesencephalic aqueduct
ponsMedulla
oblongata
hypothalamus
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背侧丘脑
小脑延髓
下丘脑
脑桥脑垂体
第四脑室
中脑水管
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The cerebellum is shaped somewhat like a butterfly. The central constricted area is called cerebellar vermis( 小脑蚓部 ), and the lateral parts are referred to as cerebellar hemispheres( 小脑半球 ).
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cerebellar vermisAnterior
lobe
posterior lobe
Primary
fissure
Horizontal fissure
Cerebellar hemisphereInferior semilunar lobule
superior semilunar lobule
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小脑上面
原裂
中央小叶山顶
山坡
水平裂
方形小叶前部
方形小叶后部
上半月小叶
下半月小叶
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Ⅰ. The lobes of Cerebellum
The cerebellum can be divided by its connections and phylogeny into three portions:
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1. The flocculonodular lobe ( 绒球小结叶 )
This lobe includes flocculus, nodule and crus of flocculus, and is predominantly vestibular in its connections.
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The flocculonodular lobe constitutes the oldest part of cerebellum, so it is called the vestibulocerebellum ( 前庭小脑 ) or archicerebellum ( 古 / 原小脑 ).
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vermis
nodule
flocculus
cerebellar tonsil
Superior cerebellar peduncle
uvulaBiventral lobule
Crus of flocculus
middle cerebellar peduncle
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小脑下面
中央小叶 小脑上脚
小脑中脚
小脑下脚
小脑扁桃体
绒球绒球脚
小节
蚓锥体 下半叶小叶
二腹小叶
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2. The anterior lobe and the rostral part of inferior verm
is
The anterior lobe, uvula and pyramid of vermis are predominantly spinocerebellar
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in its connections and is phylogenetically the next part to appear, it is also called the spinocerebellum( 脊髓小脑 ) or paleocerebellum ( 旧小脑 ).
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vermisAnterior lobe
posterior lobe
Primary
fissure
Horizontal fissure
Cerebellar hemisphereInferior semilunar lobule
Inferior semilunar lobule
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小脑上面
原裂
中央小叶山顶
山坡
水平裂
方形小叶前部
方形小叶后部
上半月小叶
下半月小叶
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vermis
cerebellar tonsil
uvula of vermis
Pyramid of vermis
Biventral lobule
Inferior semilunar lo
bule
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vermis
nodule
flocculus
cerebellar tonsil
Superior cerebellar peduncle
uvula of vermisPyramid of vermis
Biventral lobule
Inferior semilunar lobule
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小脑下面
中央小叶 小脑上脚
小脑中脚
小脑下脚
小脑扁桃体
绒球绒球脚
小节
蚓锥体 下半月小叶
二腹小叶
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3. The posterior lobe
This lobe is the largest one and include the portions of cerebellar hemispheres posterior to the primary fissure. It is predominantly
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corticopontocerebellar in its connections and constitutes the cerebrocerebellum( 大脑小脑 ) or neocerebellum ( 新小脑 ).
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vermisAnterior lobe
posterior lobe
Primary
fissure
Horizontal fissure
Cerebellar hemisphereInferior semilunar lobule
superior semilunar lobule
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vermis
nodule
flocculus
cerebellar tonsil
Superior cerebellar peduncle
uvulaPyramid of vermis
Biventral lobule
Inferior semilunar lobule
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Ⅱ. The cerebellar cortex
The cerebellar cortex is uniformly structured in all parts and consists of three layers. From exterior to interior, they are: molecular layer, Purkinje cell layer and granular layer.
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molecular layer
Purkinje cell
layergranular layer
Purkinje cell
Mossy fibers
climbing fibersAxon of Purkinje
cell
Basket cell
Golgi cell
granular cell
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There are two types of afferent fibers to the cercerebellar cortex: Mossy fibers( 苔藓纤维 ) and climbing fibers ( 攀缘纤维 ).
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Mossy fibers terminate in synaptic contact with cells of the granular layer, through which they affect the Purkinje Cells.
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The climbing fibers enter the molecular layer and wind around the dendrites of Purkinje cells. The only fibers leaving the cerebellar cortex are axons of Purkinje cells, which terminate in central
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nuclei of the cerebellum with the exception of some fibers from the cortex of the flocculonodular lobe (they enter the brain stem).
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Ⅲ. The central nuclei of cerebellum
There are four pairs of nuclei in the medullary center: the fastigial nuclei( 顶核 ), globose nuclei ( 球状核 ), emboliform and dentate nuclei ( 齿状核 ).
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Fastigial nucleus
Globose nucleus
Emboliform nucleus
Dendate nucleus
Cerebellar cortex
Cerebellar medullary subatance
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The fastigial nucleus receives the fibers from the archicerebellum. Most fibers from this nucleus end in the vestibular nuclei of both sides and the reticular formation of medulla oblongata by inferior cerebellar peduncle.
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The dentate nucleus receives fibers from cerebellar cortex. The efferent fibers of it end in the red nucleus and the thalamus of contralateral side by the superior cerebellar peduncle.
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Ⅳ. The cerebellar peduncles
1. The inferior cerebellar peduncle (restiform body/ 绳状体 )
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cerebellar tonsil
Superior cerebellar peduncle
Dendate nucleus
middle cerebellar peduncle
inferior cerebellar peduncle
Medulla oblongata
Lateral lemniscus
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cerebellar tonsil
Superior cerebellar peduncle
Dendate nucleus
middle cerebellar peduncle
inferior cerebellar peduncle
Medulla oblongata
Lateral lemniscus
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The inferior cerebellar peduncle is composed of olivocerebellar tract, posterior spinocerebllar tract and the fibers from reticular formation of medulla oblongata, vestibular nuclei and vestibular nerve.
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It also contains the efferent fibers which arise from the flocculonodular lobe and fastigial nucleus to the vestibular nuclei and the reticular formation of medulla oblongata and pons.
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2. The middle cerebellar peduncle (brachium pontis/脑桥臂 )
It is almost composed of the pontocerebellar fibers .
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3. The superior cerebellar peduncle (brachium conjunc
tivum/ 结合臂 )
It connects the cerebellum with the midbrain and thalamus and consists mainly
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of the efferent fibers from the globose, emboliform and dentate nuclei. It also contains afferent fibers, such as the anterior spinocerebellar tract.
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Superior cerebellar p
eduncle
Dendate nucleus
Trigeminal nerve
vermis
middle cerebellar peduncle
Inferior colliculus Mesencephalic aqueduct
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Superior cerebellar peduncle
Dendate nucleus
Trigeminal nerve
vermis
middle cerebellar peduncle
Inferior colliculus
Mesencephalic aqueduct
Dendate nucleus
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Ⅴ. Functions of cerebellum
1.coordinates the movements of skeletal muscles in the body;
2.maintains the equilibrium and controls the posture of the body;
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3. Modulates the muscle
tone(the tonicity of
muscles );
4.predicts the future
posture of a body part in
the movements.
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